title: Nonlinear estimation of neural processing time from BOLD signal with application to decision-making.
abstract: The extraction of information about neural activity timing from BOLD signal is a challenging task as the shape of the BOLD curve does not directly reflect the temporal characteristics of electrical activity of neurons. In this work, we introduce the concept of neural processing time (NPT) as a parameter of the biophysical model of the hemodynamic response function (HRF). Through this new concept we aim to infer more accurately the duration of neuronal response from the highly nonlinear BOLD effect. The face validity and applicability of the concept of NPT are evaluated through simulations and analysis of experimental time series. The results of both simulation and application were compared with summary measures of HRF shape. The experiment that was analyzed consisted of a decision-making paradigm with simultaneous emotional distracters. We hypothesize that the NPT in primary sensory areas, like the fusiform gyrus, is approximately the stimulus presentation duration. On the other hand, in areas related to processing of an emotional distracter, the NPT should depend on the experimental condition. As predicted, the NPT in fusiform gyrus is close to the stimulus duration and the NPT in dorsal anterior cingulate gyrus depends on the presence of an emotional distracter. Interestingly, the NPT in right but not left dorsal lateral prefrontal cortex depends on the stimulus emotional content. The summary measures of HRF obtained by a standard approach did not detect the variations observed in the NPT.
authors.affiliation: NIF-LIM-44, InRad, FMUSP, Universidade de São Paulo, Brazil. cbiazoli@gmail.com
authors.forename: Claudinei Eduardo
authors.initials: CE
authors.lastname: Biazoli
authors.forename: João Ricardo
authors.initials: JR
authors.lastname: Sato
authors.forename: Ellison Fernando
authors.initials: EF
authors.lastname: Cardoso
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Brammer
authors.forename: Edson
authors.initials: E
authors.lastname: Amaro
mesh_terms: D000465:Algorithms; D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D003198:Computer Simulation; D003657:Decision Making / Q000502:physiology*; D006179:Gyrus Cinguli / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D017711:Nonlinear Dynamics; D010100:Oxygen / Q000097:blood / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology*
chemical_list: D010100:Oxygen